Cinematograph apparatus



J. T. WELLS.

CINEMATOGRAPH APPARATUS. APPLICATION FILED FEB. 26, 19 21."

1,438,278, v Patented Dec. 12, 1922.

/Z 45 0 Z 24 I8 IU /9 g 2/ mvmam 1o ec. 12, 19220 ,nazvs.

Original application filed January To allwhom itrmay concern:

Be it known thatl, JOHN T. WELLS, a citizen of the United States, and resident of the city of Montreal, in the Province of Quebec and Dominion of Canada, have invented certain new and useful Improvements in Cinematograph Apparatus, of which the following is a full, clear, and exact description.

This invention is a division from my application Serial Number 493166, filed J anuary 22nd, 1921, and relates to improvements in cinematograph apparatus, and the object of the invention is to provide improved mechanism for shifting film in either taking, printing or projecting apparatus.

The film shifting mechanism at present in general use operates in a manner to bring the film, at each shift, suddenly from a condition of rest to a condition of movement at maximum speed, with the result that electric discharges occur between the film and an adjacent stationary part, due to static charge on the film. These discharges manifest as sparks are sufiiciently luminous to cause full local exposure of the film with the result that when developed black spots or streaks are found in various places and detract from the value and efiect of the picture.

It has been found that if the filmis moved slowly at first, the discharge takes place without sparking and that, when the film is in motion and the discharge has occurred, the speed may be greatly increased for short periods of time without causing sparking.

According to the present invention sparking is overcome and static lines on films entirely avoided by the use of mechanism which sets the film in motion at a low speed and gradually increases the speed to the desired maximum. I

The mechanism comprises essentially a member to operatively engage the film and a specially shaped cam to o erate said mem her. The mechanism may e of the claw or oscillating type illustrated, which intermittently engages the film, but it will be understood that the'underlying principle and the actuating means may. be applied equally well in mechanism having continuous engagement with the film.

' portion OINEMATOGRAPH PATUS.

22, 1921, Serial No. 439,166. Divided and this application filed February 26, 1821. Serial Ito. 447,968.

In the drawings which illustrate'the invent1on;

Fig. 1 is aside elevation of one form of mechanism. j a

Fig. 2 is a plan view. of the mechanism shown in Figure 1. Referring more particularly to the drawings, 11 deslgnates a rotatable cam having two operatmg. portions, namely an end face 12 and a circumferential rib 13. The face andthe rib'each comprise two ofiset portions each substantially parallel with the back of the cam and connected by relatively mchned, diametrically opposite portions 14 and 15 respectively; The portions 14 of the cam end face are reversely and symmetrically curved, so that the inclination of each adually increases to an intermedlate pomt and then gradually decreases. Thus, movement in the axial direction derived at the centre of the portion from a given angular movement will be much greater'than similar movement derived toward either end of the portion from an equal angular movement. From the foregoing it follows that 'a number of lines passing through diametrically opposite points on the inclined portions all intersect at a common point in theaxial line of the cam. The inclined portions 15 of the rib need .not"exactly parallel the portions 14 and may be more sharply inclined, as shown.

The mechanism operated by the cam comprises essentially a lever 16 pivoted at 17, preferably at a point in the axial line of the cam and preferably so laced in the lever that the lever engages t e cam at substantially diametrically opposite points. The

.lever may take many forms, only one of which is illustrated. The lever shown is T- shaped, having a tail 18 and a head 19. The pivotal point 17 is located in the tail close to the head and the extremities of the head bear against the cam face 12 at diametrically opposite points, so as to be rocked about the pivot point 17 upon rotation of the cam. This double engagement of the lever and cam provides for positive movement of the lever at all times and obviates the use of s rings or other means to hold the lever to the cam or to assist the cam.

In a mechanism of the type illustrated in which the film is intermittentl engaged, the film engaging member 20 is sli ably mounted on the tail of the lever and reciprocated thereon to engage and disengage the film by any suitable means, such as a rod or stem 21 rigidly connected to the member 20 and notched to engage the rib 13. It will be understood, however, that when the film is continuously engaged by its shifting member the rod 21' and rib 13 will be dispensed with and suitable connection established between the lever tail and the shifting member to produce film movement in one direction only.

In order to support the rod 21, a lug 22 is provided projecting laterally from the lever tail and preferably carrylng a guide 23 in which the rod 21 slides, the guide being of such length that the rod will be held against rocking or oscillating independently of the lever tail. It is convenient in manufacture to bend the lever tail laterally, as shown, to form the lug 22 and to continue the tail by means of a post 24- on which the member 20 may slide. The post must be regarded a part of the tail" and included in the terms lever and taiL? This method of construction enables the post to be set intermediate the lever head and rod so as to reduce the offset and relieve the mechanism of part of the stress, which would result if the post was located in line with the cam axis or if member 20 was mounted in axial alignment with the rod 21. The ofiset arrangement of the parts 21 and 24 permits the cylindrical formation of these members as the parts 21 and 25 being connected hold one another against rotation out of proper.

position and the expense and difliculty of using a polygonal rod and guide therefor are avoided.

The film engaging member 20 illustrated comprises an elongated bearing portion 25 slidable on the post 24 and carrying a cross bar 26 armed at each end with a plurality of teeth 27, suitably spaced to engage in two or'more of the apertures 28 found at each edge of a film 29.

The film is supported, where engaged by the member 20, by a suitably formed plate 30, and is held against movement away from this plate upon disengagement of the member 20 by a second suitably formed plate 31.

When the cam rotates, it causes oscillation of the lever in gradually increasing amount, proportional to the angular movement of the cam, and therefore when the cam rotates at constant speed the lever moves at gradually increasing speed, up to the needed maximum and then at decreasing speed, so that it gets into motion and comes to rest without any jerk. The film engaging member carried by the lever thus moves the film in the same manner, with the result that any static discharge is controlled and sparking avoided together with vibration ease-7e due to sudden starting and stopping of the film. In the type of mechanism illustrated, the cam rib 13 reciprocates the rod 21 fixed to the member 20 and controls the engagement with and disengagement from the film, so that engagement occurs during lever movement in one direction only, the member 20 being disengaged prior to the commencement 0 reverse movement. In the case of a film shifting member in continuous engagement with the film, the connection between the lever and shifting member must necessarily be of a character to produce a similar result, i. e., to avoid reciprocation of the film. The inclined portions 15 of the cam rib are dimensioned and located relatively to the portion 14:, 'in such a manner that the member 20 engages with and disengages from the film during the periods that the lever and film are stationary, i. e., while the lever head is riding on the parallel portions of the cam. When the inclined portions 14: of the cam are passing under and oscillating the lever, the rod 21 is engaged with the parallel portions of the rib and the member 20 is thus held stationary on the post 24, except for a very slight movement due to the arcuate movement of the notched end of the rod 21.

Having thus described my invention, what I claim is:

1. Film shifting mechanism comprising a film engaging member, a cam and a lever operatively connected with the engaging member and engaging the cam at diametrically opposite points, said lever being pivotally mounted at a point in the axial line of the cam.

2. Film shifting mechanism comprising a cam having substantially parallel ofi'set por- 105 tions and relatively inclined diametricallyv opposite portions connecting the parallel portions and so formed that lines drawn between diametrically opposite points on the inclined portions intersect at a common 110 point in the axial line of the cam, an oscillatable lever engaging the cam and a film engaging member operatively connected with the lever.

3. A device according to claim 2, in which 115 the lever is pivoted at a point in axial line of the camand engages diametrically opposite points of the cam.

4:. Film shifting mechanism comprising a cam, a pivoted lever engagin the cam, and 120 a film engaging member sli able relatively to said lever and carried thereby, said film engaging member being slidable in a direcition at right angles to the pivotal axis of the ever.

5. Film shifting mechanism comprising a cam, a lever pivoted in the axial line of the cam and engaging the cam at diametrically opposite points and a film engaging member slidably mounted on said lever.

6. In combination with a device according to claim 5, means carried by the lever for shifting the film engaging member.

7. In combination with a device according to claim 5, a second cam, and operative connection between the second cam and film engaging means for shifting the latter on the lever.

8. In combination with a device according to claim 2, a second cam having substantiallyparallel offset portions and inclined portions connecting the parallel portions and means engaging said second cam and operative to reciprocate the film engaging memher on the lever.

9. Film shifting mechanism comprising a cam having two separate operating faces, each including a pair of substantially parallel offset portions and a pair of relatively inclined portions connecting the parallel portions, a lever pivoted in the axial line of the cam and engaging one of the faces at diametrically opposite points to be oscillated by the cam, a film engaging member 0nd face of the cam to slide said member on the lever at the extremities of lever travel.

10. A device according to claim 9, in which the inclined portions of the two cam faces are located at corresponding points in the circumference of the cam and the rod engages the second face at a point intermediate the points of engagement of the lever with the first face.

11. Film shifting mechanism comprising a cam, a pivoted lever, a film shifting device mounted on the lever and movable relatively thereto, said cam presenting two cam surfaces, one engageable with-the lever to operate the same and the other engageable with said film shifting device to move the latter relatively to the lever and into and out of engagement with the film.

slidably mounted on said lever, and a rod 2'5 In witness whereof, I have hereunto set 45 my hand.

JOHN T. WELLS. 

